Gypsum is a very soft mineral composed of calcium sulphate dihydrate and often occurs in nature as flattened and often twinned crystals and transparent cleavable masses called selenite. This book presents research data from around the globe in the study of gypsum including the mining activity and geotechnical and hydreological issues related to the presence of gypsum in Asturias, Spain; the effects of flue gas desulfurisation gypsum on the performances of cement based materials; the biomechanical and biological evidences supporting the in vitro application of gypsum in three decisive spinal surgical processes and luminescence spectroscopy as a sensor for the setting of gypsum plaster.